Sustainable Immobilization of Zn, Pb, and As in Lead Smelting Slag via Fe-S(II) Microencapsulation for Heavy Metal Recycling and Environmental Remediation

Keyi Xiang, Ruosong Xie (), Guangfei Qu (), Zhishuncheng Li, Yongheng Yuan, Rui Xu and Chenyang Zhao
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Keyi Xiang: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Ruosong Xie: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Guangfei Qu: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Zhishuncheng Li: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Yongheng Yuan: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Rui Xu: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Chenyang Zhao: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China

Sustainability, 2025, vol. 17, issue 12, 1-18

Abstract: Heavy metals in lead refining waste slag pose persistent environmental risks, challenging conventional treatment methods that struggle to balance long-term stabilization with resource recovery potential. To address this issue, we developed a sustainable stabilization strategy. The simultaneous and long-lasting stabilization of Zn, Pb, and As heavy metals in lead refining waste slag was achieved by using an Fe-S(II) stabilizer, and the leaching toxicity of Zn, As and Pb was less than 1 mg/L, which is lower than the concentration limit of the Identification standards for hazardous wastes–Identification for extraction toxicity (GB5085.3-2007). The samples were analyzed by characterization before and after stabilization, and it was found that Fe-S(II) formed a protective layer of sulfide capsule on the surface of the samples. This stabilization mechanism, which has been termed the “nucleation-capture-sulfide encapsulation” process, involves after the oxidation of Fe 0 to form a core–shell structure for trapping metal ions, where the external oxide layer undergoes mineralization via S(II) sulfide reduction. This microencapsulation-based passivation not only ensures long-term heavy metal immobilization but also preserves the slag’s potential for secondary resource recovery, aligning with circular economy principles. By minimizing environmental leakage risks while retaining metal reclamation feasibility, this approach offers a green and sustainable solution for heavy-metal-laden industrial waste management.

Keywords: microencapsulated passivation; lead refining slag; simultaneous multi-metal passivation; long-term stabilization; sustainable development (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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